Hydrogen Excess Ratio Control of Ejector-based Hydrogen Recirculation PEM Fuel Cell System

Proton Exchange Membrane Fuel Cell (PEMFC) which is considered as one of the most potential promising power sources has become a hot topic. Efficient recirculation of the unused hydrogen under dynamic operation status has become a challenge for system performance evaluation, internal humidity management and system control. In this paper, an Ejector-based PEMFC (EHR-PEMFC) system is proposed to realize the hydrogen supply, recirculation and control. Control-orientated nonlinear dynamic models for the electrochemical process, ejector, and supply manifold are developed study the dynamic characteristics of the EHR-PEMFC and validated by comparing voltage polarization curve with the available data from literature. A PID control strategy is proposed to control the hydrogen excess ratio, an indicator to evaluate system efficiency, by regulating hydrogen flow valve. Simulation investigation of the control strategy for proposed EHR-PEMFC has been performed under various load demands in MATLAB/Simulink environment. The results show that the proposed EHR-PEMFC can achieve unconsumed hydrogen recirculation efficiently and hydrogen excess ratio can be controlled with satisfactory response speed and control accuracy.